The Daily Mail reports that David Latimer fashioned this terrarium out of a " ten gallon carboy, or globular bottle, which once con...

Monday, June 11, 2012

Q and A: Gnats in terrarium (from the archive)

I am at a conference and will be sharing posts from the archive this week.

Question: A few weeks ago I put together two terrariums: one with irish moss and african violet... recently I've noticed that they both have some tiny little whitish/yellowish bugs roaming around inside. I've only seen 5-6 in each one, but now I'm wondering if they're going to become a problem for the plants if they're not kept in check. I'm pretty sure that the bugs have begun to sprout wings, so I think they're probably fungus gnats that were stowed away in the potting soil.

My question is this: what's the best way to deal with these little guys?

Answer: The appearance of gnats might be the most difficult and disastrous problem for terrarium owners. Whether the gnats invade an established terrarium through an open top or appear in a freshly-planted terrarium they are very difficult to eradicate. Traditional methods for dealing with fungus gnats such as dish soap sprays and changing soil do not bode well for the delicate environment within the terrarium.

When my large jug terrarium showed signs of gnats I was desperate to try to save the arrangement. I used a sharp bamboo skewer to "turn" the soil in the terrarium to try to disrupt any of the juvenile insects or the eggs. I also used a the round end of the skewer to squash any of the flying gnats I could reach.

After careful monitoring and repeated gnat-attacks I seemed to have eliminated all but a few of the insects. I stuck some double-ended tape on the edge of the skewer to fish the last few gnats out on the makeshift fly paper.

I'm proud to say I finally saved the big terrarium from the gnat invasion and I'm happy to say it's till growing strong! However now I keep a bit of gauze over the top of the bottle to prevent any more new residents.

Good luck with the gnats and in the future- always use sterilized fresh potting soil to make your terrarium substrate.